Does fmt.Println receive any type of argument?

Question

How does fmt.Println work? Why I can pass an int or a string to it?

How can I make the code below work?

package main

import "fmt"

func ln(a interface{}) {
    fmt.Println(a)
}

func main() {
    ln(123)
    ln("test")
}

Answer 1

For example,

package main

import "fmt"

func ln(a interface{}) {
    fmt.Println(a)
}

func main() {
    ln(123)
    ln("test")
}

Output:

123
test

func Println

func Println(a ...interface{}) (n int, err error)

The Go fmt package uses the reflect package.